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Masaru Yamamoto Last modified date:2024.05.02

Graduate School

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 Reseacher Profiling Tool Kyushu University Pure
Academic Degree
Field of Specialization
Atmospheric dynamics
Outline Activities
(1)Marine meteorology over the East Asian marginal seas
(2)Dynamics of planetary middle atmosphere
I supervise students studying the above topics.
Research Interests
  • Marine meteorology in marginal sea areas of East Asia
    keyword : atmospheric dynamics
    2005.09Parameterization of microphysical processes for aerosol transport model..
  • Dynamics of planetary middle atmosphere
    keyword : Planetary science
    1993.04Atmospheric dynamics of Earth and Venus..
Academic Activities
1. Masaru Yamamoto, Kohei Ikeda, Masaaki Takahashi, Atmospheric response to high-resolution topographical and radiative forcings in a general circulation model of Venus: Time-mean structures of waves and variances, Icarus, 10.1016/j.icarus.2020.114154, 355, Article ID 114154, 2021.02, Thermal tides, stationary waves, and general circulation are investigated using a T63 Venus general circulation model (GCM) with solar and thermal radiative transfer in the presence of high-resolution surface topography, based on time average analysis. The simulated wind and static stability are very similar to the observed ones (e.g., Horinouchi et al., 2018, Ando et al. 2020). The simulated thermal tides accelerate an equatorial superrotational flow with a speed of ~90 m s−1 around the cloud-heating maximum (~65 km). The zonal-flow acceleration rates of 0.2-0.5 m s−1 Earth day−1 are produced by both horizontal and vertical momentum fluxes at low latitudes. In the GCM simulation, strong solar heating above the cloud top (>69 km) and infrared heating around the cloud bottom (~50 km) modify the vertical structures of thermal tides and their vertical momentum fluxes, which accelerate zonal flow at 103 Pa (~75 km) and 104 Pa (~65 km) at the equator and around 103 Pa at high latitudes.
Below and in the cloud layer, surface topography weakens the zonal-mean zonal flow over the Aphrodite Terra and Maxwell Montes, whereas it enhances the zonal flow in the southern polar region. The high-resolution topography produces stationary fine-scale bow structures at the cloud top and locally modifies the variances in the geographical coordinates (i.e., the activity of unsteady wave components). Over the high mountains, vertical spikes of the vertical wind variance are found, indicating penetrative plumes and gravity waves. Negative momentum flux is also locally enhanced at the cloud top over the equatorial high mountains. In the solar-fixed coordinate system, the variances (i.e., the activity of waves other than thermal tides) of flow are relatively higher on the nightside than on the dayside at the cloud top. Strong dependences of the eddy heat and momentum fluxes on local time are predominant. The local-time variation of the vertical eddy momentum flux is produced by both thermal tides and solar-related, small-scale gravity waves on the nightside..
2. Masaru Yamamoto, Kohei Ikeda, Masaaki Takahashi, Takeshi Horinouchi, Solar-locked and geographical atmospheric structures inferred from a Venus general circulation model with radiative transfer, Icarus, 10.1016/j.icarus.2018.11.015, 321, 232-250, 2019.03.
3. Masaru Yamamoto, Masaaki Takahashi, Effects of polar indirect circulation on superrotation and multiple equilibrium in long-term AGCM experiments with an idealized Venus-like forcing: sensitivity to horizontal resolution and initial condition, Journal of Geophysical Research - Planets, 123, 708-728, 2018.03.
4. Masaru Yamamoto, Masaaki Takahashi, General circulation driven by baroclinic forcing due to cloud-layer heating: significance of planetary rotation and polar eddy heat transport, Journal of Geophysical Research - Planets, 121, 558-573, 2016.04.
5. Masaru Yamamoto, Effects of a semi-enclosed ocean on extratropical cyclogenesis: the dynamical processes around the Japan Sea on 23-25 January 2008, Journal of Geophysical Research, DOI:10.1002/jgrd.50802, 118, pp.10391-10404, 2013.08.
6. Yamamoto, M. and M. Takahashi, Venusian middle-atmospheric dynamics in the presence of a strong planetary-scale 5.5-day wave, Icarus , doi:10.1016/j.icarus.2011.06.017, 217, 702-713, 2012.01.
7. Yamamoto, M. T. Ohigashi, K. Tsuboki and N. Hirose, Cloud-resolving simulation of heavy snowfalls in Japan for late December 2005: application of ocean data assimilation to a snow disaster case, Natural Hazards and Earth System Sciences, 11, 2555-2565, 2011.09.
8. Yamamoto, M. and N. Hirose, Possible modification of atmospheric circulation over the northwestern Pacific induced by a small semi-enclosed ocean, Geophysical Research Letters, doi:10.1029/2010GL046214, 38, L03804, 2011.02.
9. Yamamoto, M., Microscale simulations of Venus’ convective adjustment and mixing near the surface: thermal and material transport , Icarus , 211, 993-1006, 2011.01.
10. Yamamoto, M. and M. Takahashi, Dynamical effects of solar heating below the cloud layer in a Venus-like atmosphere, Journal of Geophysical Research -Planets, doi:10.1029/2009JE003381, 114, E12004, 2009.12.
11. Yamamoto, M. and N. Hirose, Regional atmospheric simulation of monthly precipitation using high-resolution SST obtained from an ocean assimilation model: Application to the wintertime Japan Sea, Monthly Weather Review, 137, 7, 2164–2174, 2009.07.
12. Yamamoto, M and M. Takahashi, Prograde and retrograde atmospheric rotation of cloud-covered terrestrial planets: Significance of astronomical parameters in the middle atmosphere, Astronomy and Astrophysics, Vol.490, L11-L14, 2008.11.
13. Yamamoto, M. and M. Takahashi, A parametric study of atmospheric superrotation on Venus-like planets: effects of oblique angle of planetary rotation axis, Geophysical Research Letters, Vol. 34, L16202, doi:10.1029/2007GL030220, 2007.08.
14. Yamamoto, M. and N. Hirose, Impact of SST reanalyzed using OGCM on weather simulation: A case of a developing cyclone in the Japan-Sea area, Geophys. Res. Lett., Vol. 34, L05808, doi:10.1029/2006GL028386, 2007.03.
15. Yamamoto, M. and M. Takahashi, Superrotation Maintained by Meridional Circulation and Waves in a Venus-Like AGCM, J. Atmos. Sci., Vol.63, No.12, pp.3296-3314, 2006.12.
16. Yamamoto, M. and M. Takahashi, An aerosol transport model based on a two-moment microphysical parameterization in the Venus middle atmosphere: Model description and preliminary experiments, J. Geophy. Res., Vol.111, E08002, doi:10.1029/2006JE002688, 2006.08.
17. Yamamoto, M. and M. Takahashi, Dynamics of Venus' superrotation: the eddy momentum transport processes newly found in a GCM, Geophys. Res. Lett., Vol.31, doi:10.1029/2004GL019518, 2004.05.
18. Yamamoto, M. and M. Takahashi, Superrotation and equatorial waves in a T21 Venus-like AGCM, Geophys. Res. Lett., Vol.30, doi:10.1029/2003GL016924, 2003.05.
19. Yamamoto, M. and M. Takahashi, The Fully Developed Superrotation Simulated by a General Circulation Model of a Venus-like Atmosphere, J. Atmos. Sci., Vol.60, pp.561-574, 2003.02.
20. Yamamoto, M., Blocky Markings and Planetary-Scale Waves in the Equatorial Cloud Layer of Venus, J. Atmos. Sci., Vol.58, pp.365-375, 2001.02.
21. Yamamoto, M. and H. Tanaka, The Venusian Y-shaped Cloud Pattern Based on an Aerosol-Transport Model, J. Atmos. Sci., Vol.55, pp.1400-1416, 1998.04.
22. Yamamoto, M. and H. Tanaka, Formation and Maintenance of the 4-Day Circulation in the Venus Middle Atmosphere, J. Atmos. Sci., Vol. 54, pp.1472-1489, 1997.06.